Evaluation of Lubricants for Production Conditions in Metal

R & D UpdateCPFEvaluation of Lubricants for ProductionConditions in Metal FormingCenter for Precision Forming (CPF)(formerly Engineering Research Center for Net Shape Manufacturing)www.cpforming.org/ www.ercnsm.orgThe Ohio State UniversityWorkshop- Lubrication in StampingSept. 18, Columbus, Ohio© Copyright Center for Precision Forming, 2006. All rights reserved.1

OutlineCPFObjectives – Evaluation of lubricants in metal formingprocesses./ Review of various tests.Tests to Evaluate Lubricants for ForgingDouble Cup Extrusion Test for cold forgingRing Compression Test for cold & hot forgingTests to Evaluate Lubricants for StampingDeep Drawing TestIroning Test at elevated temperatureModified Limiting Dome Height TestTests to Evaluate Lubricants for HydroformingThe Guiding Zone / Expansion Zone Tests© Copyright Center for Precision Forming, 2006. All rights reserved.2

Tests to Evaluate Lubricants for Forging- Double Cup Extrusion TestCPFDouble cup extrusion tooling (ERC/NSM)The ratio of the cup heights,R ch =h 1 /h 2 , increases withincreasing coefficient of friction(or friction factor, m)© Copyright Center for Precision Forming, 2006. All rights reserved.3

Tests to Evaluate Lubricants for Forging- Double Cup Extrusion TestCPFPerformance Evaluation Criteria:• Cup height ratio (R ch = h1 / h2) is used to rank lubricants.• Surface analysis on the cut specimen to investigate galling.• The friction factor (m) is determined by comparing experimentalresults and FE predictions of cup height ratio (R ch ) vs. stroke.h 1 h 2Initial billetFormed billet© Copyright Center for Precision Forming, 2006. All rights reserved.4

Friction factor (m)Tests to Evaluate Lubricants for Forging- Double Cup Extrusion TestAlternatives to Zinc Phosphate Coating Based LubricationCPF0.080.070.060.050.040.030.020.010Zinc PhosphateCoating + SoapMECHOMATMCIZ-CoatDaidoAqualubThe performance comparison between zinc phosphate and thethree tested lubricants shows the potential for replacing zincphosphate for mild forging processes.© Copyright Center for Precision Forming, 2006. All rights reserved.5

Tests to Evaluate Lubricants for Forging- Double Cup Extrusion TestCPFList of Recently Published Reports and Papers1. Schrader, T., Shirgaokar, M. and Altan, T., “Analysis of Double Cup Extrusion Test forEvaluation of Lubricants”, Proceedings, Int. Seminar on Precision Forging, Mar. 21-24,Nara, Japan, Paper No. 576 (2006).2. Report No. ERC/NSM-05-R-13 entitled “Evaluation of Lubricant Performance in ColdForging operations and Fundamental study of the Double Cup Extrusion Test” (2005).3. Report No. ERC/NSM-05-R-13 entitled “A Cold Forming Coating / Lubricant Study (ACollaborative Study between Henkel Surface Technologies and The Ohio StateUniversity)” (2005).4. Report No. F/ERC/NSM-02-R-85 entitled “Development of Replacements forPhoscoating used in Forging, Extrusion and Metal Forming Processes” (2002)5. Kim, H., Shriniwas, P. and Altan, T "Evaluation of New Lubricants for Cold ForgingWithout Zinc Phosphate Coating", Proceedings of the International Cold Forging Group37th Plenary Meeting, Istanbul, Turkey, Sep. 13-15, Paper No. 525-1 (2004).6. Gariety, M., Ngaile, G. and Altan. T. "Evaluation of Environmentally Friendly Lubricantsfor Cold Forging Processes", submitted to the International Journal of Machine Tool andManufacture, July, Paper No. 525 (2003).© Copyright Center for Precision Forming, 2006. All rights reserved.6

Tests to Evaluate Lubricants for Forging- Ring Compression TestCPF• Evaluation of lubricant performance (RT ~ 200ºC)• Investigation of the effect of surface topography (i.e. surfaceroughness or the real contact area ratio) on friction and lubrication• Investigation of friction in function of stroke and locationR iR i- The reduction of inner diameter (R i ) indicates the friction on ring surface© Copyright Center for Precision Forming, 2006. All rights reserved.7

Tests to Evaluate Lubricants for Forging- Ring Compression TestEffect of die temperature on lubrication conditionTest ConditionsFinal Ring GeometriesCPFRC1Lubricated (top & bottom)TD:150 °CBD, Ring: 25 °CSpeed: 65mm/secRC2ID: 19.78 mm (top), 20.56 mm (bottom)ID: 19.81 mm (top & bottom)Lubricated (top & bottom)TD,BD,Ring:150 °CSpeed: 65mm/secDry (top)Lubricated (bottom)TD,BD,Ring:150 °CSpeed: 65mm/secRC3ID: 18.71 mm (top), 19.98 mm (bottom)[ Note: TD = the top die, and BD = the bottom die, initial ring dimensions: OD / ID / height = 35/18/18 mm,made from AISI 1018 HR steel ]8© Copyright Center for Precision Forming, 2006. All rights reserved.

Tests to Evaluate Lubricants for Forging- Ring Compression TestCPFList of Recently Published Reports1. Report No. PF/ERC/NSM-05-R-14 entitled “Investigation of Friction in MetalForming Using The Ring Compression Test (Phase I: Effects of SurfaceTopography on Friction)” (2005).2. Report No. PF/ERC/NSM-04-R-28 entitled “Investigation of the Effect ofTemperature on Lubrication and Flow Stress in Cold Forming Using the RingCompression Test” (2005).3. Report No. PF/ERC/NSM-04-R-21 entitled “Micro-Tribology for Metal forming – ALiterature Review” (2004).4. Altan, T. and Kim, H., “Experimental and Numerical Studies on Friction &Lubrication in Metal Forming Processes”, submitted to Proceedings of the NSFDesign, Service, and Manufacturing Grantees and Research Conference, St.Louis, Missouri, July (2006).© Copyright Center for Precision Forming, 2006. All rights reserved.9

Evaluation of Stamping Lubricants-System ApproachStamping process as a system (e.g., the deep drawing process)CPF1. Workpiece material / Blank2. Tooling3. Interface4. Deformation zone5. Equipment6. Part7. Environment© Copyright Center for Precision Forming, 2006. All rights reserved.10

Stamping lubricants in theautomotive industryCPFProcess with oil-based (wet) lubricantDecoiling andcuttingPre-Oiling(optional)AdditionalOiling(optional)Degreasing(optional)StackingBlanks(dry orpre-oiled)Deep Drawing +subsequentblankingoperations[Courtesy: M. Pfestorf, 2005, BMW ]© Copyright Center for Precision Forming, 2006. All rights reserved.11

Stamping lubricants in theautomotive industryCPFProcess with dry-film lubricantDecoiling / Recoilingwith Lube coating byimmersion or sprayingDecoilingand cuttingStackingBlanksDeep Drawing +subsequent blankingoperationsHot bath[Courtesy: M. Pfestorf, 2005, BMW ]© Copyright Center for Precision Forming, 2006. All rights reserved.12

The Twist Compression Test (TCT)CPFr = 12.7 mmThe tool is rotated under axial force. Thetorque is measured. COF is calculated in realtime.© Copyright Center for Precision Forming, 2006. All rights reserved.13

Scratch and Slider TestsCPFa) Ball scratching test[Carlsson et al. 2001]b) Slider-on-sheet test [Heideet al. 2003]© Copyright Center for Precision Forming, 2006. All rights reserved.14

Strip Reduction TestCPFa) Strip reduction test[Olsson et al. 2004]b) Cross sectional view[Olsson et al. 2004]© Copyright Center for Precision Forming, 2006. All rights reserved.15

Strip Draw TestsCPFa) Strip draw test[Vermerulen et al. 2001]b) Draw bead simulator forgalling [Vermerulen et al.2001]© Copyright Center for Precision Forming, 2006. All rights reserved.16

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFDeep drawing test was used successfully for evaluating lubricants byvarious European manufacturers. ERC/NSM is further developing this testfor quantitative ranking of lubricants.12 inchInitialblank6 inchDeepdrawn cupSchematic of ERC/NSM Drawing Tooling© Copyright Center for Precision Forming, 2006. All rights reserved.17

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFAs blank holder pressure (P b ) increases, frictional stress () increasesbased on Coulomb’s law.Schematic of deep drawingCoulomb’s law where = the frictional shear stress the coefficient of frictionP = the blank holder pressure© Copyright Center for Precision Forming, 2006. All rights reserved.P bb18

FE simulation of deep drawing- Temperature distribution at the final drawn cupCPFSimulation parametersPunch diameter = 152.4 mmSheet diameter = 304.8 mmPunch velocity = 70 mm/secBHF = 300 KN(Sheet material : DP590 and Thickness=1.24 mm)[FEM Code: DEFORM-2D]© Copyright Center for Precision Forming, 2006. All rights reserved.19

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFPerformance Evaluation Criteria:• The max. drawing load attained.• The max. applicable blank holder force without failure of thecup.• Measurement of draw-in length, Ld, or perimeter of flange ina drawn cup.• Evaluation of lubricant build-up on the die for dry filmlubricant.© Copyright Center for Precision Forming, 2006. All rights reserved.20

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFLubricants are ranked based on the highest constant BHF thatcan be applied in the deep drawing before the cup failsBHF = 50 tonsTest speed = 65 mm/secLoad-stroke curves of formed vs. fractured cups© Copyright Center for Precision Forming, 2006. All rights reserved.21

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFComparison of Draw-in length for various lubes tested under different BHF© Copyright Center for Precision Forming, 2006. All rights reserved.22

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFList of Recently Published Papers1. Kim, H. and Altan, T., “Evaluation of Dry Film Lubricants for Stamping under RealisticProduction Conditions”, accepted to Stamping Journal, Mar. 2006 (Paper No. 579).2. Kim, H. and Altan, T., "Evaluation of Dry Film Lubricants for Automotive Applications - PartI: A General Review", R&D Update, Stamping Journal, September 2005, p.38 (Paper No.555-9).3. Kim, H. and Altan, T., “Evaluation of Dry Film Lubricants for Automotive Applications – PartII: The Ironing Test”, R&D Update, Stamping Journal, to be published in October 2005(Paper No. 555-10).4. Kim, H. and Altan, T., “Evaluation of Dry Film Lubricants for Automotive Applications – PartIII: Testing through Deep Drawing”, R&D Update, Stamping Journal, to be published inNovember 2005 (Paper No. 555-11).5. Kim, H. and Altan, T., “Performance Evaluation of Tool Materials and Lubricants in FormingGalvanized AHSS”, CIRP Annals, 2008, p. 299 (Paper No.611).6. Kim, H. and Altan, T., “Investigation of Galling in Forming Galvanized AHSS Using TCT”,JMPT, 2008, p. 459 (Paper No. 605).© Copyright Center for Precision Forming, 2006. All rights reserved.23

Tests to Evaluate Lubricants for Stamping- Deep Drawing TestCPFList of Recently Published Papers (cont.)7. “Lubrication and Galling in Stamping of Galvanized AHSS.”Part I- Stamping Journal, Jan/Feb 2008, p. 22Part II- Stamping Journal, March 2008, p. 22Part III- Stamping Journal, April 2008, p. 18© Copyright Center for Precision Forming, 2006. All rights reserved.24

Strip Drawing Test (SDT)CPFThe strip drawing test (SDT) was developed to test the higher grades ofAHSS (DP780, TRIP780 and DP980), because the limited formability ofthese steels makes the deep drawing test difficult to conduct.© Copyright Center for Precision Forming, 2006. All rights reserved.25

Strip Drawing Test (SDT)CPFDimensions of strip:Length = 356 mmWidth = 25 mmWith preliminary FE simulations of SDT, four different die radii of 5, 8, 10and 12 mm were determined to change the contact pressure in the range of110 ~ 260 MPa without any necking of strip.© Copyright Center for Precision Forming, 2006. All rights reserved.26

Tests to Evaluate Lubricants for Stamping- Ironing Test at the elevated temperatureCPFIroning Test developed at ERC/NSM successfully reproducesproduction conditions (contact pressure up to 650 MPa (94.2ksi) and temperature up to 150ºC (302ºF) in a laboratory setup.a) Ironing test at ERC/NSM, b) Ironing die with heating deviceThe ironing test was used to determine the performance of dryfilmlubricants under production conditions.© Copyright Center for Precision Forming, 2006. All rights reserved.27

Ironing Load [ton]Coating loss weight/unit area [g/m^2]Tests to Evaluate Lubricants for Stamping- Ironing Test at the elevated temperatureCPFThe performance of lubricants is evaluated based on the followingevaluation criteria:• The maximum ironing load attained.• Surface topography of the ironed cups after test.• Cup side-wall thinning.• Temperature range at which the lubricant fails.• Coating weight loss or lubricant build-up on die.16.0014.00Lub BLub A65Initial coating weight per unit area: 6.5 g/m^212.0010.0048.006.004.00322.0010.000.00 10.00 20.00 30.00 40.00 50.000Stroke [mm]Lub A© Copyright Center for Precision Forming, 2006. All rights reserved.Lub B28

Strip Drawing / Strip Ironing Test- Test ResultsCPFGalled die surface after testing 40 specimens(20 drawings and 20 ironings)DrawingIroningPmax=116 MPaPmax=450 MPa[FEM Code: PAM-STAMP 2G]Tested strip samples© Copyright Center for Precision Forming, 2006. All rights reserved.29

Strip Drawing / Strip Ironing Tests- Micrographs of Die Surfaces after testsCPF© Copyright Center for Precision Forming, 2006. All rights reserved.30

Tests to Evaluate Lubricants for Stamping- Ironing Test at the elevated temperatureCPFList of Recently Published Papers1. Chandrasekharan, S., Palaniswamy, H., Jain, N. and Altan, T "Evaluation ofStamping Lubricants at Various Temperature Levels using the Ironing Test", TheInternational Journal of Machine Tools & Manufacture, November 2003 (PaperNo. 539)2. ERC/NSM "Evaluation of Stamping Lubricants using the Ironing Test", R&DUpdate, Stamping Journal, November/December, 2003, p.50 (Paper No. 501-6)© Copyright Center for Precision Forming, 2006. All rights reserved.31

Tests to Evaluate Lubricants for Hydroforming- The Guiding Zone TestCPFFriction Test for the Guiding ZoneThis test is based on pressurizing the tubular specimen to the requiredpressure level and pushing it through a cylindrical die. This tooling usesviscous material to pressurize the tube instead of hydraulic oil.Test results© Copyright Center for Precision Forming, 2006. All rights reserved.32

Tests to Evaluate Lubricants for Hydroforming- The Guiding Zone TestCPF© Copyright Center for Precision Forming, 2006. All rights reserved.33

Tests to Evaluate Lubricants for Hydroforming- The Expansion Zone TestCPF© Copyright Center for Precision Forming, 2006. All rights reserved.34

Protrusion height PH [mm]Protrusion height indicates lubricant performance72.57271.57170.5DtubeDtubeTests to Evaluate Lubricants for Hydroformingm- The Expansion Zone TestRcornerRcurv5mmSpecimen material SS304DtubeALtriIncreasing interface frictionCDBCPFDieTube7069.56968.5PH68Lub A Lub E Lub D Lub B No LubLubricants© Copyright Center for Precision Forming, 2006. All rights reserved.35

Tests to Evaluate Lubricants for Hydroforming–The Guiding / Expansion zone TestsCPFList of Recently Published Reports and Papers1. Altan, T. and Kim, H., “Improvement of Tribological Conditions in Tube Hydroforming by UsingTextured Tubes”, submitted to Proceedings of the NSF Grantee's Conference, Scottsdale,Arizona, January 2005 (Paper No. 551).2. Ngaile, G., Gariety, M., and Altan, T. "Enhancing Tribological Conditions in Tube Hydroforming byUsing Textured Tubes", submitted to ASME Journal of Tribology, February 2004 (Paper No. 524).3. Ngaile, G., Jaeger, S., and Altan T. "Lubrication in Tube Hydroforming-Part I., Transition andExpansion Zones", Journal of Materials Processing Technology, Volume 146, Issue 1 , pp.108-115 (Paper No. 436).4. Siegert, K., et al "Evaluation of Lubrication in Tube Hydroforming", Production Engr., vol. X, Nr. 1,2003, pp.23 (Paper No. 529).5. Ngaile, G., Jaeger, S., and Altan T. "Lubrication in Tube Hydroforming-Part II., LDH Test and PearShaped Expansion Test" , Journal of Materials Processing Technology, Volume 146, Issue 1,pp.116-123 (Paper No. 437).6. Cho, H. & Altan, T. "Determination of Flow Stress and Interface Friction at Elevated Temperaturesby Inverse Analysis Technique" submitted to Journal of Materials Processing Technology, Aug,2004 (Paper No. 520).7. Cho, H., Ngaile, G. and Altan, T. "Simultaneous Determination of Flow Stress and InterfaceFriction by Finite Element Based Inverse Analysis Technique, annals of CIRP, Vol.1, 2003,pp.221 (Paper No. 516).© Copyright Center for Precision Forming, 2006. All rights reserved.36

Summary/ ConclusionsCPF• Laboratory tests used to evaluate the performance oflubricants (and additives) must emulate theproduction conditions at material/ tool interface (i.e.pressure, relative velocity, temperature, surface/coating conditions).• Several tests are available for rapid and preliminaryevaluation of lubricants (twist compression, stripdraw, stamping lubricant tester, etc.).• Deep drawing and ironing tests, conducted inproduction type equipment, can emulate the processconditions that exist in production.© Copyright Center for Precision Forming, 2006. All rights reserved.37